SOR 2019 (SOR '19: Symposium on Operational Research) Proceedings of the 15th International Symposium on Operational Research, September 25-27, 2019 (Bled, Slovenia) - Stirn, Lidija Zadnik; Žerovnik, Janez; Borštar, M. Kljajić; Arnerić, Josip; Bogataj, Marija (Slovenian Society Informatika, 2019)